Sending SMS Messages
Yes, if your phone number is SMS-enabled, you can use it to send SMS messages. A list of countries where Twilio offers SMS-enabled phone numbers and their capabilities can be found here.
Please note that local SMS-enabled phone numbers can only be used to send messages domestically.
Receiving SMS Messages
Phone numbers that are Global SMS Enabled in most cases can receive SMS messages from both domestic and international phone numbers. However, because it is the responsibility of the sending carrier to deliver the message to our network, we cannot guarantee delivery from all international carriers. We have seen increased issues with SMS messages not reaching Twilio when sent from mobile phones which are roaming internationally.
Domestic SMS Enabled phone numbers can only receive SMS messages sent domestically. While Twilio does not block any incoming messages, messages sent from international phone numbers to these local numbers will likely not be received.
Note that Twilio offers two types of SMS enabled phone numbers in the United Kingdom. Local SMS enabled phone numbers can only be used domestically within the UK, whereas mobile UK numbers can be used domestically and internationally.
Twilio also offers two types of SMS enabled phone numbers in the United States and Canada. Toll-free phone numbers which can only send and receive text messages domestically within the two countries as well as local numbers that can be used domestically and internationally.